1. Field of the Invention
The present invention relates to a thin-film magnetic head which performs a magnetic recording action by a perpendicular recording scheme, a method of manufacturing the same, a head gimbal assembly, and a hard disk drive.
2. Related Background Art
In recent years, hard disk drives have remarkably been improving their areal recording density. The areal recording density of hard disks has recently reached and is about to exceed 160 to 200 GB/platter in particular. In keeping with this trend, thin-film magnetic heads have been required to improve their performances.
The thin-film magnetic heads can roughly be classified according to their recording schemes into those of longitudinal magnetic recording type and those of perpendicular magnetic recording type. The longitudinal magnetic recording scheme records data in a (longitudinal) direction within a recording surface of a hard disk (recording medium), while the perpendicular magnetic recording scheme records data such that the direction of recording magnetization formed in the hard disk is made perpendicular to the recording surface. The thin-film magnetic heads of perpendicular magnetic recording type have been considered more promising than those of longitudinal magnetic recording type, since they can realize a much higher recording density than that in the longitudinal magnetic recording scheme, while their recorded hard disks are less susceptible to heat fluctuation.
Conventional thin-film magnetic heads of perpendicular magnetic recording type are disclosed in U.S. Pat. Nos. 6,504,675, 4,656,546, and 4,672,493 and Japanese Patent Application Laid-Open No. 2004-94997, for example.
Meanwhile, a conventional magnetic head of perpendicular magnetic recording type (perpendicular magnetic recording head which will also be referred to as “PMR” in the following) has a magnetic pole layer and a thin-film coil. The magnetic pole layer generates a recording magnetic field for recording data onto a recording medium by the perpendicular magnetic recording scheme. The thin-film coil generates a magnetic field corresponding to the data to be recorded on the recording medium.
A conventional PMR has a connecting part connecting a magnetic pole layer and a write shield layer to each other, for example, while being separated from a medium-opposing surface (also referred to as air bearing surface or ABS). In the case of this PMR, a thin-film coil is wound like a flat spiral about the connecting part.
As this kind of PMR, thin-film magnetic heads 400, 410 shown in FIGS. 27 and 28, respectively, have been known, for example. The thin-film magnetic head 400 has a thin-film coil 404 equipped with four turn parts 403a, 403b, 403c, 403d between an ABS 401 and a write shield layer 402. The thin-film magnetic head 410 has a thin-film coil 414 equipped with three turn parts 413a, 413b, 413c. 